1. Technical Field
The present disclosure relates to a light emitting diode and the manufacturing method thereof and, in particular, to a flip chip type light emitting diode and the manufacturing method thereof.
2. Description of Related Art
Conventional manufacturing method of light emitting diode (LED) packages typically places a plurality of gold balls on the electrodes of a substrate, and uses eutectic bonding to electrically couple flip chip type LED chips with corresponding electrodes of the substrate. Afterwards, an electrically insulating colloid (hereinafter referred to as “underfill”) is supplied to fill the space between the LED chips and the substrate to enhance the reflectivity. Accordingly, with flip chip method, the issue of light blocking with horizontal type chip electrode that results in lower illumination efficiency may be avoided. However, misalignment may exist when bonding LED chips to the substrate by flip chip method, causing non-uniformity in the illumination. Moreover, coating the underfill between LED chips and substrate tends to result in higher manufacturing costs in addition to undesirable reflectivity.
A conventional flip chip type LED typically has an N-type semiconductor layer, a P-type semiconductor layer, and a light-emitting layer. A plurality of metallic conductive plugs traverse through the flip chip type LED from the P-type semiconductor layer through the light-emitting layer and to the N-type semiconductor layer. An N-type electrode at a bottom surface of the flip chip type LED is connected to a plurality of the metallic conductive plugs. A P-type electrode at the bottom surface of the flip chip type LED is connected to P-type semiconductor layer. Subsequently, by either eutectic bonding or reflow, the flip chip type LED is electrically coupled to electrodes on a substrate without using gold balls for the electrical coupling. This approach not only addresses the issue of misalignment when bonding LED chips to the substrate by flip chip method, but also avoids the need of the underfill. However, in electrically coupling the flip chip type LED and the substrate under this approach, due to the close proximity between the semiconductor layers (mesa or epi) and the substrate electrodes, reverse current and short circuit may result after eutectic bonding or reflow.